Variable inductance device



June 20, 1939. F. o'r'ro VARIABLE INDUC'I'ANCE DEVICE Fil ed May s, 19:56

2 Sheets-Sheet l Fig.5.

June 20, 1939. F, om, 2,163,448

VARIABLE I NDUCTANCE DEVICE Fil'ed May 5, 1936 2 Sheets-Sheet 2 Patented June 20, 1939 UNITED STATES 2,163,441: VARIABLE mnuc'rancansvroa Franz Otto, Ncu-Finkenkrug, near Berlin, Germany, assignor to Steam-Magnesia Aktlengesellschai't, Berlin, Germany Application May 5, 1936, Serial No. 78,004 In Germany July 2, 1935 11 Claims.

This invention relates to induction apparatus, particularly for high frequency circuits using a compressed iron powder core, and has for its object to provide apparatus of this class, which is of compact design and can be readily installed.

The employment of iron powder cores brought about a considerable economy in space over the formerly used air core coils, but this advantage was partly lost in the known types of self-induction coils using such cores for the reason that the means for the adjustment oi. the iron powder core were made quite bulky. As it is desirable in most instances to balance the inductance value of the unit by moving a part of the iron powder core, it is necessary to construct the ad justing means as compactly as possible. This is.

of particular importance in apparatus in the communication art, wherein, as arule, not only one but several induction coils are employed which must be arranged as free from coupling as possible, i. e., with the axes of the coils disposed vertically to one another.

All these requirements are met by apparatus constructed according to the present invention which consists in providing an insulating member the outline of which is in the form of a cube comprising, besides means for supporting the coil windings and the iron powder core, a means for adjusting a part of the iron powder core. Such an insulating member affords the advantage that at any position of the axis of the coil it can be assembled with other cubic insulating members of the same kind to form units having any desired value of inductance, each of which is individually adjustable.

Figure 1 is an elevational view of an insulating body constructed in accordance with the present invention; Fig. 2 is a section on line 2-2 of Fig. 1; Fig. 3 is a section on line 3-3 oi Fig. 1; Fig.

4 is a vertical sectional view of a modified form of the device; Fig. 5 is a section on line 5-5 of Fig. 4; Figs. 6 and 7 illustrate afurther modification in vertical section and in plan view, of a body having a core of the spool type; Fig. 8 is another modification of the device; Fig. 9 is a vertical sectional view of a modified form of the device equipped with a simplified arrangement for adjusting the core member; Fig. 10 is a vertical section of another modification of the invention in which the core is divided into three parts; and Figs. 11 and 12 are each sectional views showing other means for adjusting the core.

Referring to the drawings, and particularly to f Figs. 1 to 8, an insulating member a is provided,

which is equi-dimensional on all sides and hence cubic in form. Chambers b for the reception of the coil winding and chambers c for the accommodation of the iron powder core are provided in the body a. A portion d of the core 5 is firmly connected with the insulating member a in any suitable manner whilst the other portion e of the core is movably disposed in the cubic insulating body a.v For adjusting the movable portion e a screw made of insulating mao terial is provided and is arranged in a semicircular trough of the insulating member a. A rib in the semicircular trough engages a groove of the screw f to prevent axial displacement thereof during its turning movement. The movable core 15 portion 6 is provided with a pressed or cut thread 9 which cooperates withthe screw so that rotation of the screw causes a longitudinal displacement of the portion e and hence changes the characteristics of the magnetic circuit. 20

The construction shown in Figs. 4 and 5 is similar to the one just described, the only diii'erence relating to the form of the core. Whereas a divided H type core is employed in the construction according to Figs. 1 to 3, the second 25 embodiment uses a shell type core divided in one plane, though the divisions may be made also in different planes. The cubic insulating member (11 is correspondingly adapted to the different form of the core.

In the embodiment shown in Figs. 6 and 7 an iron powder core is employed which has the form of a yam spool. For adjusting the induction value of the device, the movable end disc h of the core is eccentrically guided in the insulating 35 member aa. By rotating the end disc h the circumference thereof is caused to be more or less coaxial with the circumference of the other end disc 1 of the spool shaped iron powder core. The insulating member a: is again cubic and adapted 40 .to the form of the core.

A further embodiment provided with a divided core of the spool type is shown in Fig. 8. The enlarged end of the core portion i1 is movable and the enlarged end disc hi firmly connected 45 with the cubic insulating body an. The cylindrical portion of the core i1 has a pressed or cut thread formed therein which cooperates with a corresponding female thread formed in the insulating member as. 50

In the construction shown in Fig. 9 the adjusting device is produced in a simpler manner. To the shaft of the movable core portion in a relatively short threaded bushing k of insulating material is secured, which cooperates with a 55 short female thread in the insulating member at. The threaded bushing k is preferably slotted and rides in the manner of an expanding ring on the shaft of the core portion is so that rotation of the core part i2 will cause it to ride in and out' of the insulating body to change the value of the inductance of the device. The construction further differs from the embodiments according to Figs. 6 to 8 in so far as instead of a stationary end disc a fixed end ring 1 is used into which the shaft of the fungiform portion i2 extends. The form of the insulating member at is adapted to that of the core and to the adjustin device.

In the construction according to Fig. 10 the core comprises two portions m and 11. secured in the insulating member as. Through both core portions m and n a screw threaded core part 0 of compressed iron powder is inserted, for which a female thread is provided in the portion n. By means of a rib p and a clearance q on the circumference of the end disc the core portion n is specially secured against rotation.

Figs. 11 and 12 show further possibilities for the adjustment of the movable portion of the iron powder core. In the construction according to Fig. 11 sloping faces t are provided on that side of the end discs of the spool shaped core portion i4 opposite from the stationary separate front face I, and a correspondingly inclined face is formed on the insulating member or. In this way, longitudinal displacement of the core portion is effected when the core is rotated.

As shown in Fig. 2, it is possible to secure in the shaft of the movable core portion is one or more pins u which engage a helical groove 12 of the insulating member, longitudinal displacement of the core portion is being caused by rotation as in the construction described above.

The insulating member is preferably made from pressed insulating materials poor in electric loss, such as polystyrol.

As set forth above, all of the modifications include a body of insulation constructed to have the outline of a cube and formed with square shouldered end portions having recesses therein for the reception of an adjustable core part. In

every instance,. the central portion of the body is provided with means to mount an energizing winding. The reactance of each unit may be varied by changing the relative positions of the divided core parts. the units combine with each other readily to produce reactors having higher values than that of-a singlegunit. Asthe outline; or'contour, of"

each unit is cubic, it will seat'against a neighboring unit with a minimum of wasted space, and the units may be combined so that the magnetic axis of the core of each unit is normal to that of a neighboring unit. In this way, there is little or no coupling or mutual inductance between the units. If desired, the units may be built up with the axis of the cores in the same line, in which case the coupling'between the combined units may be utilized. In any event, the adjusting means for the core may be kept readily accessible regardless of the relative position of each unit to its neighbor.

I claim:-

1. A reactor of the class described, including a body of insulating material having a pair of opposed sides each formed with an outwardly facing recess connected by a bore, said bore being It will be appreciated that of smaller cross-sectional area than the crosssectional area of the recesses in a plane normal to the axis of said bore, and a core received in the bore and having parts disposed in said recesses.

2. A reactor of the class described, including a substantially cubical body of insulating material having a pair of opposed sides each formed with an outwardly facing recess and connected by a bore, said bore being of smaller cross-sectional area than the cross-sectional area of the recesses in a plane normal to the axis of said bore, and a core received in the bore and having parts disposed in said recesses.

3. A reactor of the class described, including an insulating body of substantially cubical form formed with a pair of opposed outwardly facing recesses connected by an unobstructed bore, said bore being of smaller cross-sectional areathan the cross-sectional area of the recesses in a plane normal to the axis of said bore, and a multi-part core' received in said bore and having parts dis-.- posed in said recesses.

Ill

4. A reactor of the class described, including an insulating body formed with a pair of opposed outwardly facing recesses connected by an unobstructed bore, said bore being of smaller cross-sectional area than the cross-sectional area of the recesses in a plane normal to the axis of said bore, and a multi-part core received in said bore and having parts disposed in said recesses.

5. A reactor of the class described, including an insulating body formed with a pair of opposed outwardly facing recesses connected by a bore, said bore being of smaller cross-sectional area than the cross-sectional area of the recesses in a plane normal to the axis of said bore, a multipart core received in said bore'and having parts disposed in said recesses, and means for adjusting the parts of the core with respect to eachother.

6. A reactor in accordance with claim 5 in which the core is spool-shaped and divided, and

said adjusting means including oppositely formed sloping faces, one of which is formed on said body and the other of which is formed on an end part of said core.

7. A reactor in accordance with claim 5 in which said core is spool-shaped and divided, and

said adjusting means including a pin carried by a part of said core and engaging a helical groove formed in said body.

-8. A reactor in accordance with claim 5 in which-said core is spool-shaped, and said adjusting means consisting of a slotted threaded bushing of insulating material cooperating with a corresponding thread formed in said body.

9. A reactor in accordance with claim 5 in which saidcore is spool-shaped, and said adjusting means consisting of a short threaded V bushing of insulating material cooperating with a corresponding thread formed in said body.

10. A reactor in accordance with claim 5 in which said core is spool-shaped, and said adjust- 

